The process D2000 Calc is a process of calculations. It executes arithmetical and logical operations on data in real time. D2000 Calc interprets systems of arithmetical and logical equations and functions, which allow calculations of given parameters and values an also controlling systems. The process is the parent of objects of Eval tag type. Values can be calculated either periodically or only after a change of input object value. The process D2000 Calc has no desktop for interaction with user.